The invention relates to a composite tool including means such as a drill, for forming holes in material and means for deburring or chamferring hole edges.
In the formation of holes in metals and other materials by means of a conventional rotary cutting tool, such as a drill, tap, reamer or mill, burrs may form at the entrance and exit ends of a through hole and in the case of a blind hole at the entrance end of the hole. Removal of the burrs by means of a conventional tool is, of course, standard manufacturing practice. Chamferring the edge of a hole involves substantially the same practice except the emphasis is more on shaping or forming a bevel. In any event, each case involves the removal of a small amount of material from the edge of a formed hole. Hence, the terms deburring and chamferring are used interchangeably in the art.
As intimated above, it has been the practice to form the desired hole in a material by means of a conventional primary tool and to later remove the burrs or form a chamfer in a separate operation by means of a special or chamferring tool. Such practice is exemplified by U.S. Pat. No. 2,657,597 to Pikering et al., and U.S. Pat. No. 3,276,294 to Kubicek, each showing the subsequent use of separate deburring or chamferring tools. Each patent also shows the performance of a deburring or chamferring operation at both the entrance and exit ends of a hole by means of a single tool. It goes without saying that the prior art procedure requiring separate operations for the primary and deburring or chamferring functions is time consuming, requires additional equipment and retards production, resulting in higher manufacturing costs.